A major concern in environmental and occupational air pollution is the hazard posed by suspected carcinogens. Unfortunately, previous carcinogenesis research has used logically indirect methods to assay the presence of carcinogens. The "C-Probe" direct passive integrating monitor, on the other hand, measures directly the mutagenic/carcinogenic chemical intermediates--epoxides of organic pollutants. This project is intended to demonstrate "proof-of-concept" for "C-Probe", by providing data on metabolic oxidation of precursors to epoxides tenerated or collected, and by determining the feasibility of "C-Probe" with aerosols of liquid pollutants. Experiments will involve optimizing procedures for preparing prototype "C-Probe" units; wet tests to determine sensitivity of indicator, loading requirements for the microsomal activation segment, and effects on baseline absorbances; solid diffusion tests to determine indicator development time; and liquid aerosol tests to determine applicability to air monitoring, sensitivity and calibration characteristics.